(1) Field of the Invention
The invention relates to the general field of liquid dispensing with particular reference to anti-reflection coatings for use in photoresist processing.
(2) Description of the Prior Art
Anti-reflection coatings (ARCs) are widely used in integrated circuit manufacturing as an aid to improving the quality of photoresist patterns. In the absence of such a coating there is the possibility that standing waves of the exposing radiation may be established within the photoresist layer, particularly if the layer that is to be patterned is a metal. It is thus common practice to coat the surfaces of metal layers with an ARC prior to the application of the photoresist.
A variety of methods are in use in the industry for applying ARCs to surfaces. The particular approach with which the present invention is concerned is spin coating wherein a liquid is dispensed onto the surface of a spinning wafer through a nozzle. We have been unable to find any prior art that teaches the dispensing system disclosed by the present invention. U.S. Pat. No. 5,536,534 shows a method of applying photoresist at a high pressure but this method differs significantly from that of the present invention.